The present invention relates to a method and an apparatus for melting and casting metals, including elemental metals and metallic alloys, under vacuum conditions. The present invention is applicable especially to metals having a great tendency to oxidize.
Applicant's French Pat. No. 1,587,403 describes a method for centrifugal casting which allows the avoidance of the appearance of "porosity" following the fill-up of the mold for members having a circular cross-section.
Applicant's French Patent Application, filed on Aug. 25, 1969, under Ser. No. 69 28 972 describes a method which permits heating the central cavity of a mold during centrifugal casting. Using this method, the metal is maintained at a convenient temperature for progressively feeding the "shrinkage holes", which form during the solidification process. The quality of the castings of oxidizable metals is improved by utilizing a permanent degasifier for the mold during the entire casting process.
Accordingly, centrifugal, non-turbulent casting, which is carried out under vacuum conditions using a centrifugal crucible, is generally known. Nevertheless, in the known process, the metal is melted externally of the mold and is then transported to the feeder apparatus of the centrifugal machine.
The present invention has for its object the improvement of the known centrifugal casting method in order to avoid the formation of oxides and other undesired chemical compounds which were previously developed subsequent to the melting process and the flow of the metal into the mold. The present invention has particular application in the molding of readily oxidizable metals which easily combine with other elements.